VHP Photo Glossary: Lava balls

Photograph by J.D. Griggs on 13
June 1983

Accretionary lava balls

Accretionary lava balls are roughly spherical masses that
form on the surface of an `a`a flow. They range in size from a
few centimeters to several meters in diameter. Lava balls grow when
a small fragment of solidified lava rolls along the surface
of an active flow and lava sticks or accretes to its surface.
The growth of a lava ball is similar to the way a giant
snowball grows when soft, sticky snow adheres to its surface
as it rolls downslope.

Photograph by J.D. Griggs on
2 July 1983

Glowing accretionary lava balls, pictured, (bottom, 0.75 m in diameter) in
front of moving `a`a flows. Both flows were erupted from Pu`u `O`o
vent on the east rift of Kilauea Volcano, Hawai`i.